1. Field
The present invention relates to optical communication equipment and, more specifically but not exclusively, to WDM (wavelength division multiplexing) devices.
2. Description of the Related Art
This section introduces aspects that may help facilitate a better understanding of the invention(s). Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
A typical WDM system uses a multiplexer at the transmitter site to join individual modulated optical signal streams together for transmission over the optical link, and a de-multiplexer at the receiver site to split the streams apart for detection and decoding. The system may also employ optical add-drop multiplexers, frequency converters, signal regenerators, and a variety of optical filtering devices, such as etalons and phase masks. To achieve seamless operation, different components of the WDM system usually are appropriately spectrally aligned to a specified frequency grid.